Systematic Screening of Drosophila Deficiency Mutations for Embryonic Phenotypes and Orphan Receptor Ligands
Figure 2
Examples of CNS phenotypes in deficiency homozygotes.
(A–H) are confocal maximum intensity projections of mAb 1D4 immunofluorescence in live-dissected stage 16 embryos (20× objective). Anterior is up. Scale bar equals 10 µm. (A) wild-type embryonic nerve cord showing three parallel longitudinal bundles on either side of the midline and no FasII positive bundles crossing the midline. (B) Staining of FasII in robo1 reveals a phenotype where axons repeatedly cross the midline in a circular fashion (arrow). This is a robo1 phenotype of ‘average’ strength. Most published robo images are of unusually strong phenotypes. (C) Df(3R)Exel7310 embryonic nerve cord has a phenotype where axons appear to circle the midline (arrow). (D) sad1/Df(3R)Exel7310 has a phenotype in which FasII positive axons cross the midline. It is weaker than the phenotype in (C), however. (E) Df(1)BSC627 and (F) Df(2L)Exel8041 also have phenotypes where axons appear to circle the midline (arrows). Each of the three phenotypes has a unique overall appearance, however. (G) In Df(3L)HD1, FasII positive axons of the inner fascicle cross the midline inappropriately (arrows). (H) Df(3R)Exel6162 has a phenotype in which the nerve cord has a normal geometry, but one commissural bundle per segment is FasII positive (arrow).